A lawyer for a Native American man who claims the letters KKK were carved into his stomach during surgery has filed a federal civil rights lawsuit against the South Dakota hospital where the operation took place, the hospital’s board of directors and others.

YouTube videos featuring 69-year-old Vern Traversie, a Lakota man who lives on the Cheyenne River Reservation, went viral in Native American communities earlier this year. In them, Traversie talks about being mistreated at the hospital and shows his abdomen. Though he himself is blind, Traversie says he was told by others that the scars left after his heart surgery form the letters.

A May rally in support of Traversie drew hundreds of people, many of whom said his story exemplifies the racism Native Americans experience in Rapid City. But others say they can’t make out the letters, including police who investigated his allegations and hospital officials. No criminal charges have been filed in the case.

Chase Iron Eyes, a lawyer for Traversie, filed a lawsuit in U.S. District Court in South Dakota against Rapid City Regional Hospital, its board of directors, physicians and TRS Surg Assist Inc. The lawsuit alleges a civil rights violation based on race and cites the scarring from Traversie’s double-bypass surgery done in August 2011 as evidence. It seeks a jury trial and damages.

“Defendants injured, carved, burned, and/or cared for Plaintiff’s abdomen in such a manner that scars resembling three letters `K’ were permanently placed on Plaintiff’s abdomen for no medically necessary purpose or reason, and in the process injured, carved, burned, and/or cared for other portions of Plaintiff’s body to cause injury, specifically his abdomen and back,” the lawsuit stated.

Tim Sughrue, chief executive of Rapid City Regional Hospital, said in a statement that the hospital will “vigorously defend this claim.”

“We at Rapid City Regional Hospital are confident the care we provide meets or exceeds standards of care and is without bias or consideration of race, religion, color, age, sex, disability, national origin, or any other classification protected by law,” he said.

Traversie said he hadn’t been aware the lawsuit was filed, although he knew a lawyer was planning to file one at some point on his behalf.

“I think the Native people have been fighting racial hatred for many years in South Dakota, but you know, it’s not all the people that are hateful toward Native Americans,” said Traversie, who recently had another heart surgery in Bismarck, N.D. “We have a good segment of our society – white society – in South Dakota that are Christian people and they get along good with the Native Americans. In my instance, I believe I’m dealing with the Ku Klux Klan, and that’s a small minority.”

Iron Eyes, a member of the Standing Rock Sioux Tribe, and Cody Hall, a member of the Cheyenne River Sioux Tribe, which Traversie belongs to, organized the May rally in an effort to bring attention to what they say is continued mistreatment of Native American people. Iron Eyes declined to comment about the lawsuit.

While Traversie’s story spurred the protest, many Native Americans who attended referred to broken treaties, unsolved murders and incarceration rates among Native Americans as their reasons for showing up. They included Dennis Banks, who helped found the American Indian Movement in the late 1960s to protest the U.S. government’s treatment of Indians and demand the government honor its treaties with Indian tribes.

South Dakota Attorney General Marty Jackley said that his office would release information in the “near future” about its investigation.